function GVerify (options) { // 创建一个图形验证码对象，接收options对象为参数
 this.options = { // 默认options参数值
  id: '', // 容器Id
  canvasId: 'verifyCanvas', // canvas的ID
  width: '80', // 默认canvas宽度
  height: '30', // 默认canvas高度
  type: 'number', // 图形验证码默认类型blend:数字字母混合类型、number:纯数字、letter:纯字母
  code: ''
 }

 if (Object.prototype.toString.call(options) === '[object Object]') { // 判断传入参数类型
  for (var i in options) { // 根据传入的参数，修改默认参数值
   this.options[i] = options[i]
  }
 } else {
  this.options.id = options
 }

 this.options.numArr = '0,1,2,3,4,5,6,7,8,9'.split(',')
 this.options.letterArr = getAllLetter()

 this._init()
 this.refresh()
}

GVerify.prototype = {
 /** 版本号**/
 version: '1.0.0',

 /** 初始化方法**/
 _init: function () {
  var con = document.getElementById(this.options.id)
  var canvas = document.createElement('canvas')
  // this.options.width = con.offsetWidth > 0 ? con.offsetWidth : '30'
  // this.options.height = con.offsetHeight > 0 ? con.offsetHeight : '30'
  this.options.width = '160'
  this.options.height = '50'
  canvas.id = this.options.canvasId
  canvas.width = this.options.width
  canvas.height = this.options.height
  canvas.style.cursor = 'pointer'
  canvas.innerHTML = '您的浏览器版本不支持canvas'
  con.appendChild(canvas)
  var parent = this
  canvas.onclick = function () {
   parent.refresh()
  }
 },

 /** 生成验证码**/
 refresh: function () {
  var canvas = document.getElementById(this.options.canvasId)
  if (canvas.getContext) {
   var ctx = canvas.getContext('2d')
  }
  ctx.textBaseline = 'middle'

  ctx.fillStyle = randomColor(180, 240)
  ctx.fillRect(0, 0, this.options.width, this.options.height)

  if (this.options.type === 'blend') { // 判断验证码类型
   var txtArr = this.options.numArr.concat(this.options.letterArr)
  } else if (this.options.type === 'number') {
   var txtArr = this.options.numArr
  } else {
   var txtArr = this.options.letterArr
  }

  for (var i = 1; i <= 4; i++) {
   var txt = txtArr[randomNum(0, txtArr.length)]
   this.options.code += txt
   ctx.font = randomNum(this.options.height / 2, this.options.height) + 'px SimHei' // 随机生成字体大小
   ctx.fillStyle = randomColor(50, 160) // 随机生成字体颜色
   ctx.shadowOffsetX = randomNum(-3, 3)
   ctx.shadowOffsetY = randomNum(-3, 3)
   ctx.shadowBlur = randomNum(-3, 3)
   ctx.shadowColor = 'rgba(0, 0, 0, 0.3)'
   var x = this.options.width / 5 * i
   var y = this.options.height / 2
   var deg = randomNum(-30, 30)
   /** 设置旋转角度和坐标原点**/
   ctx.translate(x, y)
   ctx.rotate(deg * Math.PI / 180)
   ctx.fillText(txt, 0, 0)
   /** 恢复旋转角度和坐标原点**/
   ctx.rotate(-deg * Math.PI / 180)
   ctx.translate(-x, -y)
  }
  /** 绘制干扰线**/
  for (var i = 0; i < 4; i++) {
   ctx.strokeStyle = randomColor(40, 180)
   ctx.beginPath()
   ctx.moveTo(randomNum(0, this.options.width), randomNum(0, this.options.height))
   ctx.lineTo(randomNum(0, this.options.width), randomNum(0, this.options.height))
   ctx.stroke()
  }
  /** 绘制干扰点**/
  for (var i = 0; i < this.options.width / 4; i++) {
   ctx.fillStyle = randomColor(0, 255)
   ctx.beginPath()
   ctx.arc(randomNum(0, this.options.width), randomNum(0, this.options.height), 1, 0, 2 * Math.PI)
   ctx.fill()
  }
 },

 /** 验证验证码**/
 validate: function (code) {
  var code = code.toLowerCase()
  var v_code = this.options.code.toLowerCase()
  if (code == v_code) {
   return true
  } else {
   return false
  }
 }
}
/** 生成字母数组**/
function getAllLetter () {
 var letterStr = 'a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z'
 return letterStr.split(',')
}
/** 生成一个随机数**/
function randomNum (min, max) {
 return Math.floor(Math.random() * (max - min) + min)
}
/** 生成一个随机色**/
function randomColor (min, max) {
 var r = randomNum(min, max)
 var g = randomNum(min, max)
 var b = randomNum(min, max)
 return 'rgb(' + r + ',' + g + ',' + b + ')'
}

export {
 GVerify
}